Heavy metal contamination is increasingly becoming recognized as a major environmental problem. Effective monitoring of releases of heavy metals poses a number of problems. Acceptable levels of heavy metals in the environment are very low for many metals; hence, very sensitive measurements must be made. Existing measurement techniques having the necessary sensitivity do not lend themselves to field conditions. Metal assays often require spectroscopic instruments that are not well suited to field use. As a result, samples must be taken, labeled with the location of the sample site, and then returned to a central laboratory for analysis. The analysis procedures typically require highly trained laboratory personnel. The need for trained personnel, expensive instrumentation, and the transportation and handling of large numbers of samples makes it difficult to provide simultaneous monitoring of a large number of sites.
In addition, the contamination of waterways and the like often results from sporadic releases. If the samples are not taken at a time that is properly correlated with that of the release, the contamination event will be missed. In principle, an ion exchange column, or the like, may be used to continuously sample the water source over a large period of time, and thereby, avoid missing the contamination event. In such systems, samples from the waterway are continuously taken and pumped through an ion exchange column. After some period of time, the column is removed and the contents analyzed for heavy metals. Unfortunately, the lifetime of an ion exchange resin in the field is quite limited. Most water sources contain naturally occurring high levels of calcium, magnesium, and/or iron. These materials rapidly saturate ion exchange resins rendering the resins incapable of collecting heavy metals. Furthermore, the continued exposure to hard water after trapping heavy metal may lead to the loss of the trapped metals by exchange reactions with the innocuous elements in the hard water. At best, an examination of the material trapped by the resin will provide information about the average levels in the body of water being sampled. As a result, a short term, high level release can be missed because the resulting concentration is below that of the measurement instruments used to analyze the material trapped on the resin.
Broadly, it is the object of the present invention to provide an improved detection system for heavy metals.
It is a further object of the present invention to provide a detection system that can be used to monitor a water source over a longer period of time than that available with existing systems.
It is a still further object of the present invention to provide a detection system that will not be swamped by innocuous background minerals that are often found in hard water sources.
It is yet another object of the present invention to provide a detection system that has greater sensitivity than existing detection systems.
These and other objects of the present invention will become apparent to those skilled in the art from the following detailed description of the invention and the accompanying drawings.